It’s now official: 2015 was the warmest year on record.
NASA and the National Oceanic and Atmospheric Administration (NOAA) today updated their separate analyses of surface temperatures across the globe, both declaring 2015’s heat to be unprecedented. Teams of scientists in Britain and Japan are expected to come to the same conclusion in the coming days.
This video summarizes NASA’s historical temperature data.
Producing a single figure for the global average temperature means combining results from monitoring stations across the world. Last year, the Berkeley Earth project, set up to address climate skeptics’ concerns about the way this was done, stopped short of declaring 2014 to be the record claimed by NASA and NOAA. Given the statistical uncertainties, the Berkeley researchers were prepared to say only that 2014 tied with 2005 and 2010.
But the heat in 2015 has been so extreme that this time there is no real doubt. Leaders of the Berkeley Earth project have already said they are 99.996% confident that last year was the warmest on record.
According to NASA’s analysis, in 2015 the Earth was 0.87 degrees C (1.57 degrees Fahrenheit) warmer than the average for 1950 to 1981 — compared to 0.74 degrees C in 2014.
See here to learn why last year broke the previous record with such ease.